1. Field of the Invention
The present invention relates to the use of lasers. In particular, the present invention relates to the field of laser safety.
2. Information Disclosure Statement
Lasers are used in a variety of industries and professions from medical to manufacturing, and have utility in countless applications. High-powered lasers in particular are used in, among others, medical and industrial applications. Such lasers must be used carefully, however, because they can be potentially damaging to users or patients who do not utilize the proper safeguards. Errant use of a high power laser can result in possible burns or ocular damage should laser light be shined in one's eye.
There are numerous laser safety systems that incorporate features such as full environmental isolation, automation, radiation shields that block or contain radiation, and trigger systems that switch lasers off when certain conditions are met.
Other approaches attempt to define a restricted area around the laser and the application through some means. These configurations generally provide that if the restricted area is breached, then the laser is somehow shut off or blocked. For example, U.S. Pat. No. 4,884,275 by Simms describes a shutoff switch used in conjunction with a hand-held infrared laser source. It is meant to shut off if someone looks into the light exit opening while it is emitting to prevent permanent or severe eye damage. Light that is reflected of an object or person within a specified distance reflects a certain intensity back to an array of photoelectric safety switches, triggering the switches and blocking the laser beam. As a result, if something comes in contact with the laser or someone looks into the beam from a dangerously close distance, the laser is blocked. This invention works to disable the beam after it has come into contact with an unintended object, but has no mechanism for preventing that person or object from approaching the beam and thus avoiding any initial contact.
U.S. Pat. No. 5,117,221 by Mishica, Jr. discloses a laser light entertainment system for use in large venues such as sports arenas. It features infrared transmitters that surround a predetermined area. If a person breaches the area, the transmitter beams are interrupted and the system will shut off. This system is effective for large scale laser uses, and is generally too complicated and expensive for use in small scale medical or industrial applications.
U.S. Pat. No. 5,301,347 by Kensky discloses a microprocessor based controller system for laser shutters. The system provides an interface at laboratory entrances, and the controller closes the shutters, thus disabling the laser beam, if there is a breach of the interface. The use of interface slot cards allows an authorized holder to use the laser and gives that holder the ability to control the shutters. This system is designed to secure an entire room, and is supported by a microprocessor for controlling the safety features.
U.S. Pat. No. 4,687,918 describes a laser pointer system consisting of a hand-held laser pointer such as those used during a lecture, a series of incoherent optical transmitters positioned around the lecture screen, and optical detectors embedded in the tip of the laser pointer that respond to the emission of the optical transmitters. As long as there is a direct line of sight between the optical transmitters and the detectors, the laser pointer is operable. If the laser pointer is directed away from the screen, it automatically switches off. The incoherent optical transmitters are preferably pulsed LEDs emitting in the IR range, and they emit radiation in a dispersed way. In order to discriminate the emitted signal from ambient light the emitted radiation is pulsed to a discriminating frequency. This invention is limited to laser pointers for presentations, and would not be suitable for other applications, especially those that require precise positioning such as medical and laser surface treatments. Additionally, this invention does not provide the ability to create a sharply defined restricted area and would not serve to protect a person who enters the area near the screen.
U.S. Pat. No. 6,130,754 describes a device for transmitting a high-power laser source that produces a high-power beam and a low power beam substantially parallel and close together or coincident. The low power beam (the barrier or cladding beam) is positioned so that an obstruction will pass through the low power beam before the high power beam. This disturbance would trigger a shut-off of the high power beam. In one embodiment, low power radiation is coaxial with and completely surrounds the smaller cross-section high-power beam, so that the high-power beam is essentially a protected core of this cladding radiation. The means to detect a disturbance in the cladding beam is integrated into the laser source, and a disturbance is detected by cladding light reflected back into the source. One disadvantage of this invention is that, although the cladding beam may serve to protect those that enter an area near the beam path, there is no restriction on the orientation of the high power beam. There is no indication that this invention will protect tissue, surfaces or persons from the beam if it is directed to a location different from the intended application or treatment area. Also, this invention is needlessly complex, as there will also be various amounts of reflection from an application surface, which would have to be taken into account. Thus, this invention would need to be calibrated for each treatment. Also, complex surfaces may require numerous calibrations which would prove time-consuming and complex and could reduce the effectiveness of the cladding beam.
The methods and apparatuses used in the state of the art can be costly, difficult to manufacture, and inconvenient. These safety devices do not allow for the flexibility in both beam movement and portability that would be desirable for certain applications and especially for medical treatments. For these applications, and for those applications where the user prefers a minimum of encumbrance, it would be useful to provide a system capable of restricting a laser beam to certain areas, or excluding a laser beam from certain areas, while allowing complete flexibility of movement in the treatment or application area.